This is honestly a very complicated question. It really depends on what role you intend to fulfill as a jungler, namely whether you want to be a tanky champ with tons of cc or a glass cannon such as shaco. The prob with playing a tanky champ is that it means that if you are playing solo que you are relying on your teammates to carry you to victory. If you have friends to play with though, a tanky jungler is easier to play. so my suggestions are as follows:
Darius, WW, Trynd, Olaf, Udyr
Udyr, WW(still good choices), Shen, Malphite,
DO NOT TRY NAUT WITHOUT A LOT OF PRACTICE. He requires skill and aslo familiarity with jungling. I also highly recommend Udyr over WW.